Greenhouse gases, primarily CO2, in the atmosphere absorb and emit thermal infra-red radiation (TIR) at different wavelengths, each with a certain bandwidth depending on pressure, temperature, path length and mixture composition, i.e. "optical thickness". Thus, the enhanced greenhouse effect is the result of these gases interfering with certain wavelengths of TIR radiation from earth to space. Therefore, as an alternative for reducing CO2 emissions from using carbon-containing fuels this paper will address: 1. how to modify the spectrum of the TIR radiation from earth, reducing the radiative forcing caused by atmospheric CO2? and 2. how to accomplish this by methods that allow for recovery of heat and/or power? Options exist for modifying the TIR spectrum from earth to space to different wavelengths or wavelength bands, using (mixtures of) so-called participating gases to create sufficient optical thickness to interfere with the TIR, focusing on the 15 μm band for CO2. Volumes (like a spacing between two windows) with different depths, CO2 volume fractions or pressures will have different emissivity (ε) and absorptivity (α) properties allow for creating temperature gradients or bodies with different temperatures. Heat engines or thermoelectric devices may be applied to generate power making use of this, using also the temperature difference between ground level surroundings (270-320 K) and sky (230-280 K). Calculations suggest that temperature gradients may be readily created using simple geometries. Power generation at several W/m2 is possible at energy conversion efficiencies similar to photovoltaic devices or transport vehicles with combustion engines.